Braking arrangement which includes hydraulic pump

ABSTRACT

A high inertia load and a hydraulic pump are both driven by a motor via a common mechanical coupling, such as a drive belt. When power is removed from the motor, fluid from the pump is diverted from its normal low impedance path and into a high impedance path. This brakes the pump and the latter brakes the high inertia load and motor via the common mechanical coupling.

United States Patent [191 Wright et al.

BRAKING ARRANGEMENT wHICH INCLUDES HYDRAULIC PUMP Inventors: David Frank Wright, Bolton;

Robert Aron Rubenstein, F ramingham, both of Mass.

Assignee: RCA Corporation, New York, NY.

Filed: Nov. 15, 1971 Appl. No.: 198,860

US. Cl 417/236, 188/290, 4-17/302, 417/317, 417/504, 417/505 Int. Cl. F04b 41/00, F16d 57/06 Field of Search 188/290; 417/27, 417/28, 208, 302-304, 317, 441, 504, 505, 236; 318/362, 370, 372

References Cited UNITED STATES PATENTS Bartholomzius 188/290 X Nov. 13, 1973 2,932,257 4/1960 Lupin 417/323 X 2,240,607 5/1941 Buck 417/28 X 2,953,902 9/1960 Arbogast 417/308 X Primary Examiner-C. J. Husar Assistant ExaminerLeonard Smith Att0rr'1ey1-1. Christoffersen ABSTRACT A high inertia load and a hydraulic pump are both driven by .a motor via a common mechanical coupling, such as a drive belt. When power is removed from the motor, fluid from the pump is diverted from its normal low impedance path and into a high impedance path. This brakes the pump and the latter brakes the high inertia load and motor via the common mechanical coupling.

5 Claims, 1 Drawing Figure POWER 68 SUPPLY BRAKING ARRANGEMENT WHICH INCLUDES HYDRAULIC PUMP BACKGROUND OF THE INVENTION In applications involving moving mechanical elements, it is often desirable to provide some sort of braking force when the driving force ceases. One example of such an apparatus is a disc file unit used with an electronic computer as a random access data storage device. In a disc file, a motor is attached to rotate a removable disc pack (a plurality of disc-shaped elements stacked one atop the other, separated by spacers, and containing magnetic information recorded on circumferential tracks on the disc surfaces). The motor also drives a hydraulic pump which provides hydraulic fluid pressure for a hydraulic actuator used to position electromagnetic transducers over desired tracks on the disc surfaces.

When power is disconnected from the motor, it is desirable to stop the disc pack as quickly as possible so that it may be removed and replaced with another disc pack. There are a number of well-known ways of doing this but each suffers from some deficiency. For example, the disc pack supporting structure may be mechanically braked but the braking elements wear and require replacement or adjustment, creating maintenance problems. Other methods of braking, such as eddy current brakes, require additional separate elements which are expensive and in themselves maintenance problems.

SUMMARY OF THE INVENTION BRIEF DESCRIPTION OF THE DRAWING The sole FIGUREis a'disc filememoryapparatus which contains the present invention.

DETAILED DESCRIPTION Referring now to the sole figure, which illustrates schematically a magnetic storage disc file 8, a drive means such as a motor is connected to drive a fluid pump 14 and a high inertia load such as a removable disc pack 16. The connection may be via gearing or, as illustrated, via belt 12 which passes over pulley attached to motor 10, pulley 22 attached to pump 14 and pulley 24 attached to disc pack l6.

rotation of the pulleys as determined by the direction of rotation of motor 10.

A pipe 46 conducts fluid 48 which, while shown as a liquid, may be a gas, from a fluid reservoir 50 to pump 14. Pump 14 may be of any conventional variety of hydraulic pump but is preferably of the constant displacement type. That is, it passes a constant volume of fluid on each pump revolution. Such a pump is characterized by requiring a driving torque which is a function of the pressure required to operate any utilization device attached to the pump. Outlet 52 of pump 14 is connected via tubing to a remotely operable valve 56 and to a relatively high pressure or high impedance first utilization device such as' a pressure relief valve 60. Pipes 62 and 63 conduct fluid from valves 56 and 60 respectively to the input of a relatively low pressure or low impedance second utilization device such as a hydraulic actuator 64. From the hydraulic actuator 64 fluid returns via pipe 65 to fluid reservoir 50. Valve 56 may be any commercially available remotely operated valve and, as illustrated, is electrically actuated from a power source 68 via switch 69. The same power source may be used to provide drive power to motor 10. Therefore, when switch 69 is closed, power is provided both to valve 56 and to motor 10. Conversely, when the switch 69 is opened, no power is provided to either of these elements. Valve 56 may be a normally closed valve. A normally closed valve is one which, when in its normal position, blocks the flow of fluid through it and when power is applied, permits fluid to flow through it from pump 14 to actuator 64.

Relief valve 60 is of conventional design employing a housing 70 containing a fluid chamber 72, a piston 74, acompression spring 76 and adjusting means 78. When fluid 48 exerts greater than some given pressure, it forces piston 76 upward (as illustrated in the figure) thereby permitting fluid to flow through orifice 79 and into chamber 72. From the chamber the fluid flows out of the relief valve, through exit port 80. The exact amount of pressure required to openpiston 74 is determined by adjusting screw 78. The required pressure may be made higher than pressure which is needed to force the fluid through actuator 64. Therefore, when The belt also passes over a tensioning mechanism 30 which provides suitable belt tension. The ,belt tension mechanism comprises a pulley 32 rotatably mounted on one end of an arm 34, the other end of which is coupled via tension spring 36 to a mechanical ground '38 such as a common frame, not shown, to which the other elements of the disc file 8 are attached. Arm 34 is pivotably attached to mechanically grounded pin 39. The force exerted by tension spring 36 causes pulley 32 to exert the desired amount of pressure on belt 12. Arrows 40 in each of the pulleys indicate the direction of valve 56 is open (i.e. permitting the flow of fluid through it), the fluid takes the pathof least resistance which is through valve 56 and no fl'uid' passes through relief valve 60. However, when witch 69 is opened thereby closing valve 56, fluid is forced through relief valve 60.

Actuator 64 is of conventional design found in many disc files such as the RCA Corporation model /594. It is responsive to electronic signals (not shown) for digitally moving a transducer carriage 84 in the direction of arrow 86. Attached to carriage 84 are a plurality of transducer assemblies 88 there being one for each disc 90 of disc pack 16. In a practical application, there may be as many as a dozen or more discs 90 and there may he transducer heads 88 on both the upper and lower surfaces of each disc 90. Each of the discs contains on its surface magnetic information coded in concentric tracks. Actuator 64, under fluid pressure, moves heads 88 to any of those concentric tracks or may move heads 88 completely off the disc pack 16 to permit removal of the pack 16 from shaft 92, the shaft being attached to pulley 24. When the actuator is not moving carriage 84, its fluid passes through a relief pressure valve 93 which is connected at its input to pipes 62 and 63 and at its output to pipe 65. It is similar to relief valve 60.

In operation, when switch 69 is closed, motor drives belt 12 and the latter drives pump 14 and disc pack 16. Hydraulic fluid 48, under pressure, flows through output 52 of pump 14 through open valve 56 and the relatively low impedance path of actuator 64. The fluid in actuator 64 is used to move carriage 84 and therefore heads 88 attached to the carriage, to position them under electronic control (from signals not shown) to desired positions on discs 90. When carriage 84 is stationary, fluid passes through valve 93 which is set to open under approximately 300 pounds per square inch pressure.

Then when it is desired to stop disc pack 16, switch 69 is opened, interrupting power to motor 10 and valve 56. Conventionally, braking of disc pack 16 was effected through a separate braking mechanism to the disc pack assembly by means (not shown). However in accordance with the invention, the switch 69 also controls the valve 56. When the switch 69'opens, the valve 56 which in its unenergized condition may be spring biased to the closed position, returns to the closed position. This stops the flow of fluid through the valve 56. Because of inertia, the disc pack 16 continues to rotate. Since it is coupled, via belt 12 to pump 14, pump 14 continues to pump fluid. The fluid exiting from exit 52 of pump 14 being blocked from flowing through valve 56 must flow instead through the high impedance path of relief valve 60. As the relief valve is typically set to open under relatively high pressure, about 500 pounds per square inch in one application, this pressure is reflected back to pump 14. This, along with any pressure requirements from actuator 64, makes for an extra pumping effort requirement. Since the pump 14 is no longer driven by motor 10, it begins to decelerate. The deacceleration rate is essentially controlled by the constant pressure required to open relief valve 60. Therefore, as the pump slows so does disc pack 16. During this time, full pressure is available to operate actuator 64 to move heads 88 off of discs 90. This is particularly from a constant torque device to a reducing torque device bringing the disc to a very gradual stop.

While there has been described one useful embodyment of the invention, other configurations are possible. For example pipe 63 could be connected, not to actuator 64, but rather directly to reservoir 48. Pipe 62 could be connected directly to the reservoir so that the so called low impedance path is in fact a substantially zero impedance path. Finally valve 56 could positively connect pump 14 to either valve 60 or pipe 62 rather than allow the fluid to follow the path of least resistance when valve 56 is closed as occurs in the device described.

What is claimed is:

l. The combination of:

a relatively high inertia load;

first fluid path exhibiting a relatively low impedance second fluid path exhibiting a relatively high impedance to the flow of fluid;

a hydraulic pump operatively connected to one end of said two fluid paths for pumping liquid therethrough;

a hydraulically operated load coupled to the opposite end of said two fluid paths for operation in response to fluid received therefrom;

drive means connected via a common mechanical coupling in driving relationship with both the hydraulic pump and the high inertia load;

means for concurrently applying power to said drive means and directing said fluid through said low impedance path, whereby said drive means drives both said hydraulic pump and said high inertia load and whereby, when power is removed from said drive means, said high inertia load tends to coast and to cause the hydraulic pump, to which it is coupled by said common mechanical coupling, to continue to pump fluid, thereby causing said hydraulically operated load to continue to operate; and

means for lessening the coasting time comprising means for directing said fluid through said high impedance path when power is removed from said mechanical drive means, whereby the hydraulic pump slowsdown in view of the higher impedance path through which it is forced to pump fluid, and said high inertia load slows down with it, due to said common mechanical coupling between said pump drive means and high inertia load.

2. In combination:

fluid path means including a relatively low impedance path and a relatively high impedance path either one of which is selectable;

pumping means connected to one end of said fluid path means, said pumping means being of the type that requires a driving torque which is a function of the impedance of the means to which said pumping means is coupled;

a hydraulically operated load connected to the other end of said path means responsive to the flow of fluid from either path for operation thereof;

a relatively high inertia load;

mechanical coupling means between said high inertia load and pumping means such that both are driven together; 1

drive means mechanically coupled to said high inertia load and said pump meansfor driving them; means for concurrently energizing said driving means and selecting said low impedance path whereby said high inertia load is driven and whereby when said driving means is tie-energized said high inertia load continues to move causing said pump means to continue pumping, causing said hydraulically operated load to continue to operate; and

means for selecting said high impedance path when said driving means is de-energized, said torque in said pump thereby increasing, whereby the rate of said high inertia load movement is slowed.

3. The combination of:

a high inertia load;

a fluid path means comprising a relatively low impedance path and a relatively high impedance path;

a hydraulic pump operatively connected to said fluid path means;

a fluid operated load;

a fluid path coupling said fluid path means to said fluid operated load for receiving fluid from said path means and applying it to said fluid operated load;

a drive motor connected via a common mechanical means for lessening the coasting time comprising means for closing said low impedance path when power is removed from said motor, whereby the hydraulic pump slows down in view of the higher impedance path through which it is forced to pump fluid, and said high inertia load slows down with it, due to said common mechanical coupling between said pump, motor and :high inertia load.

4. The combination as set forth in claim 1 wherein said hydraulic pump is a constant displacement pump characterized by requiring a driving torque which is a function of the fluid impedance of the apparatus coupled to said pump.

5. The combination as set forth in claim 4 wherein said high impedance path includes a pressure relief valve. 

1. The combination of: a relatively high inertia load; first fluid path exhibiting a relatively low impedance to the flow of fluid; second fluid path exhibiting a relatively high impedance to the flow of fluid; a hydraulic pump operatively connected to one end of said two fluid paths for pumping liquid therethrough; a hydraulically operated load coupled to the opposite end of said two fluid paths for operation in response to fluid received therefrom; drive means connected via a common mechanical coupling in driving relationship with both the hydraulic pump and the high inertia load; means for concurrently applying power to said drive means and directing said fluid through said low impedance path, whereby said drive means drives both said hydraulic pump and said high inertia load and whereby, when power is removed from said drive means, said high inertia load tends to coast and to cause the hydraulic pump, to which it is coupled by said common mechanical coupling, to continue to pump fluid, thereby causing said hydraulically operated load to continue to operate; and means for lessening the coasting time comprising means for directing said fluid through said high impedance path when power is removed from said mechanical drive means, whereby the hydraulic pump slows down in view of the higher impedance path through which it is forcEd to pump fluid, and said high inertia load slows down with it, due to said common mechanical coupling between said pump drive means and high inertia load.
 2. In combination: fluid path means including a relatively low impedance path and a relatively high impedance path either one of which is selectable; pumping means connected to one end of said fluid path means, said pumping means being of the type that requires a driving torque which is a function of the impedance of the means to which said pumping means is coupled; a hydraulically operated load connected to the other end of said path means responsive to the flow of fluid from either path for operation thereof; a relatively high inertia load; mechanical coupling means between said high inertia load and pumping means such that both are driven together; drive means mechanically coupled to said high inertia load and said pump means for driving them; means for concurrently energizing said driving means and selecting said low impedance path whereby said high inertia load is driven and whereby when said driving means is de-energized said high inertia load continues to move causing said pump means to continue pumping, causing said hydraulically operated load to continue to operate; and means for selecting said high impedance path when said driving means is de-energized, said torque in said pump thereby increasing, whereby the rate of said high inertia load movement is slowed.
 3. The combination of: a high inertia load; a fluid path means comprising a relatively low impedance path and a relatively high impedance path; a hydraulic pump operatively connected to said fluid path means; a fluid operated load; a fluid path coupling said fluid path means to said fluid operated load for receiving fluid from said path means and applying it to said fluid operated load; a drive motor connected via a common mechanical coupling in driving relationship with both the hydraulic pump and the high inertia load, whereby when power is applied to said motor, the hydraulic pump drives fluid at least mainly into the low impedance path and drives also the high inertia load, and when power is removed from the motor, the high inertia load tends to coast and to cause the hydraulic pump, to which it is coupled by said common mechanical coupling, to continue to pump fluid; and means for lessening the coasting time comprising means for closing said low impedance path when power is removed from said motor, whereby the hydraulic pump slows down in view of the higher impedance path through which it is forced to pump fluid, and said high inertia load slows down with it, due to said common mechanical coupling between said pump, motor and high inertia load.
 4. The combination as set forth in claim 1 wherein said hydraulic pump is a constant displacement pump characterized by requiring a driving torque which is a function of the fluid impedance of the apparatus coupled to said pump.
 5. The combination as set forth in claim 4 wherein said high impedance path includes a pressure relief valve. 